1. Field of the Invention
This invention generally relates to a multi-way loudspeaker system and in particular to a multi-way loudspeaker system comprised of a symmetric arrangement of loudspeaker drivers in a two-dimensional plane capable of achieving high-quality sound for use in connection with stereo loudspeaker systems, multi-channel home entertainment systems and public address systems.
2. Related Art
Loudspeaker designers are constantly striving to design controlled directivity loudspeaker systems that achieve high quality sound across a wide range of frequency bands while limiting the size and number of transducers (i.e. drivers) in the system, as well as the required number of amplifiers (i.e. ways) in the system. Achieving such a high quality sound across a wide frequency range has been challenging due to the variation in size of the transducers across the dedicated parts of the audio frequency band and the constraints in spacing between the transducers.
High-quality loudspeakers for the audio frequency ranges generally employ multiple, specialized drivers for dedicated parts of the audio frequency band, such as tweeters (generally 2 kHz-20 kHz), midrange drivers (generally 200 Hz-5 kHz), and woofers (generally 20 Hz-1 kHz). Typically the higher frequency drivers are smaller in size than the lower frequency drivers.
To achieve a high sound quality, it is desirable to position the drivers in the loudspeaker as closely as possible to one another. However, because of the physical sizes of the specialized drivers, the ability to position the drivers in close proximity to one another is limited. The farther the drivers are positioned from one another, the more acoustic problems arise.
Because of the spacing between drivers due to their physical size, which is comparable with the wavelength of the radiated sound, the acoustic outputs of the drivers sum up to the intended flat, frequency-independent response only on a single line perpendicular to the loudspeaker, usually at the so-called acoustic center. Outside of that axis, frequency responses are more or less distorted due to interferences caused by different path lengths of sound waves traveling from the drivers to the considered points in space. Thus, there have been many attempts in history to build loudspeakers with a controlled sound field over a larger space with smooth out-of-axis responses.
The current state of art for controlling sound field in large spaces, such as public spaces, is to utilize uniform coverage horns for sound reinforcement. However, the use of uniform coverage horns has its disadvantages, as the uniform coverage horns have a limited frequency range, fixed, non-steerable polar patterns, and relatively high distortion.
Current two-dimensional arrays for surround sound in home entertainment, so-called sound projectors, are linearly spaced arrays of identical, small wide band drivers. This type of array is capable of producing multiple sound beams, which radiate into the room, and, while bouncing back from walls to the listener, produce the desired surround effect. However, since the drivers in the two-dimensional, linearly spaced arrays are identical, the maximum sound pressure level, and sound quality of the sound projector is limited to the capabilities of the transducers, which is in general rather poor, compared with drive units that are optimized for a dedicated frequency band. Further, the sound projector employs a very high number of drivers that all need to be driven individually, which leads to high implementation complexity and high cost.
Thus, a need still exists for a high-quality, low-distortion, two-dimensional loudspeaker configuration that employs a minimum number of transducers, as well as amplifiers, where the transducers are optimized for high performance by utilizing specialized drivers, such as tweeters, midrange drivers or woofers, across the audio frequency band. A further need still exists for a two-dimensional loudspeaker configuration to electronically alter beam widths and steering angles on site, as opposed to fixed installations using horn arrays.